The invention relates to a method of operating a motor vehicle with at least one electric drive component, which is cooled via at least one cooling circuit.
The power output of electrically operated motor vehicles is largely determined by the thermal capacity of the electric drive components, such as motor, power electronics, DC-DC converter, battery and the like. Therefore, at least one coolant circuit is typically provided, by which heat can be removed from those components and discharged to the ambient air using a heat exchanger. To ensure additional cooling, this coolant circuit is also frequently coupled to a refrigerant circuit of the motor vehicle.
During the operation of the refrigerant circuit, a coolant is compressed and thereby liquefied, and then cooled via an ambient heat exchanger. A partial volume flow of the coolant is converted back into the gas phase in a first evaporator, thereby further cooling the coolant. Air which after exiting the evaporator is directed into the interior of the motor vehicle flows through this evaporator for climate control of the interior of the motor vehicle. Another partial volume flow passes through a second evaporator which is in thermal contact with the coolant circuit for cooling the electrical drive components. In this way, a flow temperature of the coolant in the coolant circuit can be set lower than the ambient temperature.
However, when the electric drive components are severely burdened, for example in a sports or racing operating mode of the motor vehicle, this is not always sufficient to ensure adequate cooling of the electric drive components. These can then only be operated with a predetermined constant power that is less than the maximum possible peak operating power. Although the continuous power can be exceeded during brief time periods, the power must be reduced again as soon as the electrical components have reached a predetermined maximum temperature.